Build Financial Tools
Into Your App
Access 326 financial calculators via a simple REST API. Mortgage, loan, investment, tax, insurance, and more — all with a single API key.
const response = await fetch("https://getnextool.com/api/v1/tools", {
method: "POST",
headers: {
"Content-Type": "application/json",
"x-api-key": "ntool_YOUR_API_KEY_HERE",
},
body: JSON.stringify({
tool: "mortgage-calculator",
inputs: {
loanAmount: 350000,
interestRate: 6.5,
loanTermYears: 30,
downPayment: 70000,
},
}),
});
const data = await response.json();
console.log(data.result);Simple, Transparent Pricing
Start free, scale as you grow. No hidden fees, no surprises. Overage is billed per-request — you never get cut off.
Free
Free forever
- 100 requests/day
- 10 req/min rate limit
- Basic calculators only
- JSON responses
- Community support
Developer
Overage: $0.002/request
- 10,000 requests/month
- 60 req/min rate limit
- All 326 calculators
- JSON + CSV responses
- Webhook support
- Email support
- API key dashboard
Business
Overage: $0.001/request
- 100,000 requests/month
- 300 req/min rate limit
- All calculators + AI tools
- All response formats
- Webhook + streaming
- Priority support
- Custom endpoints
- SLA 99.9%
Enterprise
Tailored to your needs
- Unlimited requests
- Custom rate limits
- Dedicated infrastructure
- Custom calculators
- White-label API
- 24/7 phone support
- SLA 99.99%
- Dedicated account manager
Built for Every Financial Use Case
From startups to enterprises, teams use the NexTool API to embed financial intelligence into their products.
Fintech Apps
Embed mortgage pre-qualification, loan comparison, and investment projections directly in your fintech product.
Financial Advisors
Power client-facing portals with retirement planning, tax estimation, and net worth calculators.
Content Publishers
Add interactive calculators to financial articles and blog posts to boost engagement and time-on-page.
Insurance Companies
Calculate premiums, compare coverage options, and estimate life insurance needs programmatically.
Real Estate Platforms
Show monthly payments, closing costs, and affordability estimates alongside property listings.
Banks & Credit Unions
Integrate loan, savings, and CD calculators into online banking portals and mobile apps.
Works With Any Language or Framework
Simple REST API with JSON responses. If your language can make HTTP requests, it can use NexTool.
Compare Plans
A detailed breakdown of what is included in each tier.
| Feature | Free | Developer | Business | Enterprise |
|---|---|---|---|---|
| Monthly requests | 100/day | 10,000 | 100,000 | Unlimited |
| Rate limit | 10/min | 60/min | 300/min | Custom |
| Calculator access | Basic only | All 326 | All + AI | All + Custom |
| Response formats | JSON | JSON, CSV | All formats | All formats |
| Webhook support | ||||
| Streaming responses | ||||
| Custom endpoints | ||||
| API key dashboard | ||||
| White-label API | ||||
| SLA guarantee | None | None | 99.9% | 99.99% |
| Support | Community | Priority | 24/7 phone | |
| Overage pricing | N/A | $0.002/req | $0.001/req | Custom |
Get Started in 3 Steps
From signup to your first API response in under 5 minutes.
Create an Account
Sign up for free and pick a plan that fits your usage. No credit card required for the Free tier.
Get Your API Key
Generate an API key from your dashboard. You can create up to 5 keys per account for different environments.
Make Your First Call
Send a POST request to /api/v1/tools with your API key and tool inputs. Get JSON results instantly.
Trusted by Developers
“We replaced three separate APIs with NexTool. One key, 326 calculators. Our integration time dropped from weeks to hours.”
“The mortgage calculator API alone saves us 40+ engineering hours per quarter. The response format is clean and consistent across all tools.”
“We embedded NexTool calculators into our financial content. Article engagement increased 3x and average session duration doubled.”
Frequently Asked Questions
How does API authentication work?
After subscribing, you will receive an API key from your dashboard. Include it in the x-api-key header with every request. Keys use the format ntool_ followed by 32 hex characters.
What happens when I exceed my request quota?
On the Free tier, additional requests return a 429 error until the daily limit resets. On paid tiers, overage requests are charged at the listed per-request rate and billed at the end of your billing cycle.
Can I upgrade or downgrade my plan at any time?
Yes. Upgrades take effect immediately with prorated billing. Downgrades take effect at the start of your next billing cycle. You will not lose any data when changing plans.
What is the SLA guarantee?
Business plans include a 99.9% uptime SLA, and Enterprise plans include 99.99%. If we fail to meet the SLA, you receive service credits as outlined in our Service Level Agreement.
Do you offer annual billing discounts?
Yes. Contact our sales team for annual billing on Developer and Business plans, which include a 20% discount. Enterprise plans always include custom billing terms.
Can I test the API before committing to a paid plan?
Absolutely. The Free tier gives you 100 requests per day with no credit card required. This is enough to prototype your integration before upgrading.
What response formats are supported?
All tiers support JSON responses. Developer and above also support CSV exports. Business and Enterprise tiers support all formats including XML, streaming JSON, and custom formats.
Is there a sandbox or staging environment?
Yes. All API keys work against both our production and sandbox environments. Sandbox requests do not count against your quota.
Need a Custom Solution?
Get unlimited requests, dedicated infrastructure, custom SLAs, and a dedicated account manager. Tell us about your needs.
No spam. Unsubscribe anytime.
Ready to Build?
Start with 100 free requests per day. No credit card required. Upgrade when you are ready to scale.